Radiotelegraphic receiving system



H. PRATT.

RADIOTELEGRAPH'IC RECEIVING SYSTEM.

APPLICATION FILED JULYZI, 1919- I Patented Feb. 1,1921.

U srATEs' PATENT oFFicE.

RADIWIPELEGRAPHIC RECEIVING SYSTEM.

Specification of Letters Patent.

. Patented Feb. 1, 1921.

Application filed July 21, 1919. Serial No. 812,454.

T 0 a'ZZ whom it mag concern."

Be it known that l, HARADEN PRA T, a citizen of the United States, and an employee of the Navy Department, residing at 1510 Lombard street, city and county of Ean Francisco, California, (whose post-office address is Bureau of Steam Engineering, Navy Department, Washington, D. U.,,) have invented an improvement in Radiotelegraphic Receiving Systems, of which the following is a specification.

My invention relates broadly to an im provement in radiotelegraphic communication and more particularly to a new method for the reception of radiotelegraphic signals and has for its object the production of useful mechanical vibrations directly through the magnetic action of radio frequency currents. r

The currents induced in radio receiving systems are ordinarily of too high a frequency to enable them to produce useful direct mechanical movements; but the tendency of the art during recent years has been toward lower frequencies, so that at the present day, frequencies are being employed for long distance communication which are suiiiciently low to enable them to produce mechanical motions directly. Certain radiotelegraphic stations have been in continuous operation for trans-Atlantic communication for over ten months past, which have been regularly employing radio frequency ourrents between 17,000 and 20,000 cycles per second. 'lu ning forks and other mechanical andv acoustic apparatus aitilizing frequencies of this order have been well known in the sciences for some time past and this. invention pertains to means for generating useful and intelligible mechanical vibrations directly obtained from currents of suchfrequenc'ies.

lln order to more clearly illustrate my in vention, ll shall describe an embodiment. thereof drawing.

in a radiotelegraphic receiving system, a source of radio frequency potential is.-sup plied by antenna 1, in circuit with condenser 2, inductance 3 and earth connection 4. The

inductance has terminals 5 and 6 connected to the input of radio frequency amplifier? andtransferred through transformer 9, by means of primar winding 8 and secondary 10 teen electrica 1y tuned circuit containing condenser 11 and an electoinagnet 13 hav in. connection with the annexed ing a winding 12. Associated with this electromagnet 1s a mechanically tuned armature 14 of steel, permanently magnetized, and

so related in position that one of its ma netic poles may be acted upon magnetical y by the electromagnet.

An alternating" radio fre quency current'flow'ing in the electromagnet 12 produces a magnetic field at the end of its core which is also alternatin thereby causing vibrations of the magnetically olarized mechanically tuned armat re, W ich are made possible through the pring action of the armature as the latter is' fastened rigidly to a fixed base 15, with: its u per end free to vibrate. The mechanical tu e of the armature must be such that its vibrations will be in synchronism with the riadio frequency current used. This mechanical vibration may be dampened by any suitable means,

such as immersing the armature in a fluid, so that such vibration will not continue after the flow of radio frequency current n the electromagnet has ceased. If this arm ture is arranged for tracing an inked reco d upon a moving cylinder 17 advanced ,y

screw 18, the radio telcgraphic'signals may be received and recorded thereon in a legible manner by means of pen 16 from the groups .of radio frequency currents generated in the system. y

Although I have speclfied above a particular application, my invention is by no means limited thereto, but applies as well. to any source of radio frequency current in a radiotelegraphic receiving system associated with a mechanical recorder with or without the use of radio frequency transformers wherein the recorder derives energy directly from such current for producing useful mechanical vibrations suitable for rendering intelligible, radiotelegraphic sigi nals impinging thereon.

\Vhat I claim and desire to secure by Let ters Patent is: t

In a radiotelcgraphic receiving system the combination of a source of radio frequency current with a tuned circuit containing ail electromagnet having an armature melt. chanlcally tuned and adapted to vibrate me-' chanically insynchronism with said radio frequency current, and means for making such vibrations useful for the intelligible reception of radio telegraphic characoers sub; stantially as described.

HARADEN PRATT. 

